Effect of lithium addition upon γ-Al2O3 for isopropanol dehydration

The effect of lithium addition to γ-Al₂O₃ on the acidity and on the catalytic behaviour in the isopropanol dehydration reaction is studied. Results show that there is an important blocking or poisoning effect of lithium on the Lewis Al³⁺ sites of the alumina surface; these sites play an important role in the isopropanol dehydration reaction to di-isopropylether and propylene. The di-isopropylether formation is drastically reduced by lithium addition, while the propylene formation can be maintained, even at a high lithium content, by increasing the reaction temperature. Results are interpreted by considering that the ether would be produced by a concerted mechanism (E₂), and the olefin formation could be carried out by both E₂ or E₁ mechanisms.     

Low-density polyethylene depth profile analysis by photoacoustic spectroscopy

Near-infrared photoacoustic spectra of polyethylene (1 mm slab) were taken in the modulation range 10–240 Hz, which corresponds to thermal diffusion layers in the 56?11 μm range. Thick-layer spectra are very similar to polyethylene film transmission spectra, but large differences are observed between the spectra taken at various modulation frequencies. From 10 to 80 Hz, all the spectral band intensities decrease linearly with ω^?a where ω is the light modulation frequency and a varies from 0.48 to 1.00 for different constituent groups. The analysis of spectral intensity as a function of modulation frequency shows that peak intensity ratios of ? CH₃, ?CH₂, and ? OH groups, relative to that of methylene groups, increase as thinner, closer-to-surface polymer layers are sampled. From this we conclude that near-to-surface layers of solid polyethylene are richer in ? CH₃, ?CH₂ and ? OH groups than the polymer bulk.     

<Emphasis Type="SmallCaps">l</Emphasis>-DOPA Increases Lignification Associated with <Emphasis Type="BoldItalic">Glycine max</Emphasis> Root Growth-Inhibition

l-3,4-dihydroxyphenylalanine (l-DOPA), an allelochemical exuded from the roots of velvet bean [Mucuna pruriens (L.) DC. var. utilis], presents a highly inhibitory action to plant growth. The effects of l-DOPA on phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) and peroxidase (POD, EC 1.11.1.7) activities, and phenolic compound and lignin content in soybean [Glycine max (L.) Merr.] roots were investigated to determine the possible phytotoxic mechanism. Three-day-old seedlings were cultivated in half-strength Hoagland nutrient solution (pH 6.0), without or with 0.1 to 1.0 mM l-DOPA in a growth chamber (25°C, 12-hr light to 12-hr darkness photoperiod, irradiance of 280 μmol m⁻² s⁻¹) for 24 hr. In general, the length, fresh weight, and dry weight of the roots decreased, whereas PAL and POD activities and phenolic compound and lignin content increased after l-DOPA treatments. Results showed the susceptibility of soybean to l-DOPA and reinforce the role of this nonprotein amino acid as a strong allelochemical. The present findings also suggest that l-DOPA-induced inhibition in soybean roots may be because of a cell wall stiffening process related to the formation of cross-linking between cell wall polymers linked to lignin production.     

短链葡聚糖包合姜黄素的分子机制

通过利用普鲁兰酶来酶解蜡质玉米淀粉而得到的短链葡聚糖来包合姜黄素,可以极大地提高姜黄素的水溶性。本研究还使用新型的计算机模拟的方法来分析短链葡聚糖和姜黄素的包合行为机制,模拟了短链葡聚糖-姜黄素包合物在600 ns内的分子包合行为。从模拟轨迹中获取的自组装快照图,可以知道包合物的结合方式是边解离边复合最后趋于稳定结构的包合方式。通过体系回转半径反应了短链葡聚糖随着时间与姜黄素包合行为过程中的构象变化,结果与快照图一致。体系溶解性较好,模拟得知的结果与实验基本一致,短链葡聚糖-姜黄素的溶解性高于单独的姜黄素水溶液,提高了姜黄素的生物利用率。为医学领域寻找合适的药物壁材提供了一种新的研究途径。     

Low Ozone Concentrations Differentially Affect the Structural and Functional Features of Non-Activated and Activated Fibroblasts In Vitro

Oxygen–ozone (O₂–O₃) therapy is increasingly applied as a complementary/adjuvant treatment for several diseases; however, the biological mechanisms accounting for the efficacy of low O₃ concentrations need further investigations to understand the possibly multiple effects on the different cell types. In this work, we focused our attention on fibroblasts as ubiquitous connective cells playing roles in the body architecture, in the homeostasis of tissue-resident cells, and in many physiological and pathological processes. Using an established human fibroblast cell line as an in vitro model, we adopted a multimodal approach to explore a panel of cell structural and functional features, combining light and electron microscopy, Western blot analysis, real-time quantitative polymerase chain reaction, and multiplex assays for cytokines. The administration of O₂–O₃ gas mixtures induced multiple effects on fibroblasts, depending on their activation state: in non-activated fibroblasts, O₃ stimulated proliferation, formation of cell surface protrusions, antioxidant response, and IL-6 and TGF-β1 secretion, while in LPS-activated fibroblasts, O₃ stimulated only antioxidant response and cytokines secretion. Therefore, the low O₃ concentrations used in this study induced activation-like responses in non-activated fibroblasts, whereas in already activated fibroblasts, the cell protective capability was potentiated.     

The Endocannabinoid System in the Mediterranean Mussel Mytilus galloprovincialis: Possible Mediators of the Immune Activity?

Anandamide (AEA) is one of the best characterized members of the endocannabinoid family and its involvement in many pathophysiological processes has been well documented in vertebrates and invertebrates. Here, we report the biochemical and functional characterization of key elements of the endocannabinoid system in hemocytes isolated from the Mediterranean mussel Mytilus galloprovincialis. We also show the effects of exogenous AEA, as well as of capsaicin, on the cell ability to migrate and to activate the respiratory burst, upon in vitro stimulation of phagocytosis. Interestingly, our findings show that both AEA and capsaicin suppress the hemocyte response and that the use of selective antagonists of CB₂ and TRPV1 receptors revert their inhibitory effects. Overall, present data support previous evidence on the presence of endocannabinoid signaling in mollusks and advance our knowledge about the evolutionary origins of this endogenous system and its role in the innate response of mollusks.     

Bioinspired glycosaminoglycan hydrogels via click chemistry for 3D dynamic cell encapsulation

Cell encapsulation within 3D hydrogels is an attractive approach to develop effective cell-based therapies. However, little is known about how cells respond to the dynamic microenvironment resulting from hydrogel gelation-based cell encapsulation. Here, a tunable biomimetic hydrogel system that possesses alterable gelation kinetics and biologically relevant matrix stiffness is developed to study 3D dynamic cellular responses during encapsulation. Hydrogels are synthesized by crosslinking thiolated hyaluronic acid and thiolated chondroitin sulfate with poly(ethylene glycol) diacrylate under cell-compatible conditions. Hydrogel properties are tailored by altering thiol substitution degrees of glycosaminoglycans or molecular weights of crosslinkers. Encapsulation of human mesenchymal stem cells through hydrogel gelation reveals high cell viability as well as a three-stage gelation-dependent cellular response in real-time focal adhesion kinase (FAK) phosphorylation in live single cells. Furthermore, stiffer hydrogels result in higher equilibrium FAK activity and enhanced actin protrusions. Our results demonstrate the promise of hydrogel-mediated cellular responses during cell encapsulation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47212.     

Kefiran films plasticized with sugars and polyols: water vapor barrier and mechanical properties in relation to their microstructure analyzed by ATR/FT-IR spectroscopy

Kefiran, an exopolysaccharide produced by microorganisms present in kefir grains, is a glucogalactan that has several health promoting properties. In the present work the effect of different sugars (glucose, galactose, sucrose) and polyols (glycerol and sorbitol) as plasticizers on kefiran film properties was evaluated. Kefiran films were brittle and rigid and all the tested plasticizers improved film properties. They were all transparent with low opacity. Unplasticized kefiran films X-ray diffraction patterns were similar to those of plasticized ones, showing an amorphous-crystalline structure with low crystallinity degree. All films presented low a_w values (below 0.5) conferring protection properties against microorganism growth. The lowest permeability value was obtained with glucose as plasticizer whereas the best mechanical properties were obtained with glycerol addition.     

A Study of the Structural, Optical and Electrical Properties of SnS Thin Films Modified by Plasma

SnS thin films were deposited by chemical bath deposition technique and treated using glow discharge 02 plasma. The pressure discharge was 3 Torr, discharge voltage of 2.5 kV and 20 mA of discharge current. The as-deposited and treated thin films were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The photoconductivity and electrical effects of SnS have been studied. The SnS thin films had an orthorhombic crystalline structure. The optical gap changed from 1.61 to 1.84 eV due to the 02 plasma treatment. The conductivity shows a marked increase with the treatment, from 2.56×10^-6 （Ω·cm）-1 for as-deposited film until 0.10 （Ω·cm）-1 for the film treated at 180 rain. This result is a suitable range of conductivity for the improvement of the solar cell with SnS as an absorber material.     

Shear bond strength of repairs in porcelain conditioned with laser

The aim of this study was to evaluate the shear bond strength of repairs in porcelain conditioned with laser. Sixty porcelain discs were made and six groups were formed (n = 10): G1: conditioning with laser with potency 760 mW; G2: conditioning with laser with potency 760 mW and application of 37% phosphoric acid for 15 s; G3: conditioning with laser with potency 900 mW; G4: conditioning with laser with potency 900 mW and application of 37% phosphoric acid for 15 s; G5: application of 37% phosphoric acid for 15 s (group control) and G6: application of 10% hydrofluoric acid for 2 min. The composite resin was insert of incremental layers at the porcelain surface aided with a metal matrix, and photoactivation for 20 s each increment. The specimens were submitted to a thermal cycling by 1000 cycles of 30 s in each bath with temperature between 5 and 55°C. After the thermal cycling, specimens were submitted to the shear bond strength. The results were evaluated statistically through analysis of variance and Tukey's tests with 5% significance. The averages and standard deviation founded were: G1, 11.25 (±3.10); G2, 12.32 (±2.65); G3, 14.02 (±2.38); G4, 13.44 (±2,07); G5, 9.91 (±2,18); G6, 12.74 (±2.67). The results showed that the femtosecond laser produced a shear bond strength of repairs in porcelain equal to the hydrofluoric acid and significantly superior to the use of phosphoric acid. Microsc. Res. Tech., 2012. © 2012 Wiley Periodicals, Inc.